Ultralow Contact Resistance of Thermal Interface Materials Enabled by the Vitrimer Chemistry of a ?-Hydroxy Phosphate Ester

Highly efficient thermal interface materials (TIMs) are crucial for high-power electronic devices; however, the high thermal contact resistance (R-c) between mating surfaces limits their application. Here, we demonstrate a malleable thermoset polymer-based TIM that has a low R-c because of its ability to conform at the contact interface. We synthesized a ss-hydroxy phosphate ester polymer (vEP, a kind of vitrimer with an associative dynamic covalent bond) and a polymer-Ag composite with conductive fillers (Ag flakes and Ag-nanoparticle-coated multiwalled carbon nanotubes). Interestingly, the total thermal resistance significantly decreased by approximately 2 orders of magnitude from 516 to 8.45 mm2 K W-1 as the temperature increased from 45 to 132 degrees C. This was mainly due to the significantly enhanced conformability and dramatic decrease in Rc at above the topology freezing transition temperature by the exchange of the dynamic covalent bonds (vEP moiety). The proposed approach based on a vitrimer matrix (vEP) could be effective for developing TIMs that effectively minimize the interfacial thermal resistance of high-power electronic devices.